This invention relates to the manufacture of manifolds for internal combustion engines.
Some engine manifolds are presently manufactured by welding stainless steel laterals to a stainless steel tubular body after connecting openings are milled or pierced into the body. The body material used has a high chromium content, causing it to be exceedingly wearing on tooling used to form these openings. Milling the openings is expensive and slow. It has the potential of leaving burrs which must be later removed. Piercing produces particularly heavy burrs as the tooling and punches wear, causing difficulty in removing the workpiece from the mandrel, and requiring subsequent burr removal operations. It also tends to deform the workpiece.